Nomor Atom dan Nomor Massa // Kimia

Summary

This video explains fundamental concepts of atomic structure, including protons, neutrons, and electrons. It covers how these particles influence the behavior of elements, with a focus on atomic numbers and mass numbers. The video elaborates on the relationship between atomic number (Z), protons, and electrons in neutral atoms and ions. It includes examples, such as the oxygen atom, to illustrate how mass number is calculated and how ionization affects atomic structure. Additionally, the video explains how to find the number of protons, neutrons, and electrons in both neutral atoms and ions.

Takeaways

• 😀 An atom consists of three main particles: electrons (negative charge), protons (positive charge), and neutrons (neutral charge).
• 😀 Electrons are found in the outer orbitals, protons are located in the nucleus, and neutrons also reside in the nucleus.
• 😀 In a neutral atom, the number of protons equals the number of electrons, ensuring a balanced charge.
• 😀 The atomic number (Z) indicates the number of protons in an atom, while the mass number (A) is the sum of protons and neutrons.
• 😀 To determine the mass number, you add the number of protons and neutrons: A = P + N.
• 😀 For a neutral atom, the number of protons is equal to the number of electrons.
• 😀 The relationship between atomic number (Z) and mass number (A) is used to calculate the number of neutrons: N = A - Z.
• 😀 Example: For oxygen (atomic number 8), it has 8 protons and 8 electrons in a neutral state.
• 😀 When an atom becomes an ion, it either loses electrons (forming a cation) or gains electrons (forming an anion).
• 😀 The number of protons and neutrons remains unchanged in ions; only the number of electrons changes.
• 😀 For an ion with a negative charge (e.g., F-), the number of electrons is greater than the number of protons, while for a positive ion (e.g., Mg2+), the number of electrons is fewer than the protons.

Q & A

What are the three main subatomic particles that make up an atom?

The three main subatomic particles that make up an atom are electrons, protons, and neutrons. Electrons have a negative charge, protons have a positive charge, and neutrons are neutral.

What is the significance of the atomic number (Z) in an atom?

The atomic number (Z) represents the number of protons in the nucleus of an atom. In a neutral atom, the number of protons equals the number of electrons.

What does the mass number (A) indicate in an atom?

The mass number (A) indicates the total number of protons and neutrons in the nucleus of an atom. It is calculated as A = P (protons) + N (neutrons).

How do you calculate the number of neutrons in an atom?

To calculate the number of neutrons, subtract the atomic number (Z) from the mass number (A): N = A - Z.

What happens when an atom becomes an ion?

When an atom becomes an ion, it either loses or gains electrons to achieve stability. A positively charged ion (cation) is formed when an atom loses electrons, and a negatively charged ion (anion) is formed when it gains electrons.

How are electrons different in an ion compared to a neutral atom?

In a neutral atom, the number of electrons equals the number of protons. However, in an ion, the number of electrons differs from the number of protons due to the loss or gain of electrons.

What is the relationship between the atomic number and protons?

The atomic number (Z) is equal to the number of protons in the nucleus of an atom. This defines the element.

What is the atomic number and mass number of calcium (Ca)?

The atomic number of calcium (Ca) is 20, and its mass number is 40. The mass number is typically rounded to the nearest whole number.

How do you determine the number of electrons in a negatively charged ion like F⁻?

For a negatively charged ion like F⁻, the number of electrons is calculated by adding the number of negative ions to the number of protons. For example, for F⁻ with an atomic number of 9, it has 10 electrons (9 protons + 1 extra electron).

How is the number of electrons calculated in a positively charged ion like Mg²⁺?

For a positively charged ion like Mg²⁺, the number of electrons is calculated by subtracting the charge of the ion from the number of protons. For example, for Mg²⁺ with an atomic number of 12, it has 10 electrons (12 protons - 2 electrons).